The invention concerns a device for assisting the actuation of a tool comprising two arms able to move in rotation about an axis. The invention applies to any type of tool as defined above. These tools are for example pliers, secateurs or the like.
Such tools are actuated by moving the arms towards each other. For this purpose, the arms are able to move in rotation between an open position in which the arms are distant from each other and a closed position in which the arms are close to each other. The forces exerted by the tool (cutting or clamping force for example) are directly proportional to the forces exerted by the user on the arms when passing from the open position to the closed position. The forces imposed on the user are therefore sometimes high and may give rise to fatigue or pain if the tool is used frequently or for operations demanding a special force.
The invention aims to mitigate these drawbacks by proposing a device for assisting the actuation of such a tool making it possible to reduce or even eliminate the forces demanded of a user for actuating the tool. For this purpose, the invention concerns a device assisting the actuation of a tool comprising two arms able to move in rotation about an axis between an open position in which the arms are distant from each other and a closed position in which the arms are close to each other, the said device comprising a cable, the end part of which is associated with one of the said arms, the other end part being disposed in a cable tensioner, the said tensioner being associated with the other arm, the said device comprising means for actuating the tensioner between an open position in which the cable is slack, the arms being in the open position, and a closed position in which the cable is tensioned so as to make the arms pass to their closed position.
According to one example embodiment, the tensioner is a winder. Thus the forces for actuating the tool are provided at least partly by the winding of the cable in the winder without the user having to effect high clamping forces about the arms in order to make them pass to the closed position. According to a variant, the tensioner consists of a screw and nut mechanism.
This solution is advantageous since the screw and nut mechanism makes it possible to dispense with the use of a reduction gear connected to the actuation means. This is because the screw and nut mechanism now includes reduction gearing. The actuation means are therefore directly connected to the screw and nut mechanism, which gives rise to significant saving in space on the device.
Preferably, the means for actuating the tensioner are separate from the tool. The term separate means that, even if the actuation means are mechanically connected to the assistance device fixed to the tool, they are not for all that fixed to this tool. This arrangement makes it possible to offset the actuation means and the batteries, which represent a load for the user, in a separate box that can be placed on a table or carried on the belt. Thus the user does not have to support the weight of the actuation means and the battery at arms length.
Advantageously, the actuation means transmit the tension force to the tensioner by means of a flexible link. The use of a flexible link makes it possible to transmit a rotation movement between two elements free with respect to each other. The flexible link is preferably integrated in an external protective sheath that also comprises at least one electric cable connecting the actuation means to the rest of the device. The electric cable transmits the control and sensor signals to the actuation means.
According to one embodiment, the actuation means comprise an electric motor. According to one embodiment, the device comprises a force sensor for the actuation of the arms by a user, the said sensor being coupled to the actuation means so that the winding force of the cable is proportional to the force for actuation of the arms by the user. Thus the user keeps the sensation of forces to be effected for actuating the tool, although these forces are considerable reduced. It is important that this sensation be preserved in order to prevent ill-advised manoeuvres of the tool (excess clamping or cutting of an object that is not desired, for example). Means for adjusting the forces exerted by the device can be provided. The user can then choose what proportion of force he wishes to keep in actuating the tool.
The device comprises a counter for the cycles of use of the tool, the said counter being arranged to count the number of passages from the open position to the closed position and/or vice versa. Thus the device makes it possible to obtain information on the service life of the tool, which may be particularly useful in the case of repeated use (in a factory for example) of this tool.